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Abstract:

An intelligent electronic device segregates urgent data frames from
non-urgent data frames on reception so that the urgent data frames may be
handled with greater priority. A switching device is disposed between an
external network interface and multiple internal network ports. Based on
a network data type indicia, urgent data frames are routed to one of the
ports, and non-urgent data frames are routed to another port. A processor
coupled to the internal network ports handles urgent data frames before
handling any non-urgent data frames.

Claims:

1. A method operating within an intelligent electronic device for
optimizing the handling of network data for the intelligent electronic
device, the intelligent electric device including an external network
interface, a first internal network port, and a second internal network
port, the method comprising the steps of:i) receiving network data at the
external network interface;ii) examining the received network data for a
network data type indicia; andiii) directing the network data to the
first internal network port if the network data type indicia is
indicative of an urgent network source.

2. The method of claim 1 further comprising the step of directing the
network data to the second internal network port if the network data type
indicia is indicative of a non-urgent network source.

6. The method of claim 1 wherein the external network interface is an
Ethernet interface.

7. The method of claim 6 wherein the intelligent electronic device further
includes an Ethernet switch integrated circuit, and wherein the step of
directing is performed by the Ethernet switch integrated circuit.

10. The method of claim 7 wherein the intelligent electronic device
further includes a packet filtering circuit, the packet filtering circuit
disposed between the external network interface and the first network
port, the method further comprising the step of filtering network data
from an urgent network source and discarding any data not intended for
the intelligent electronic device.

11. The method of claim 10 wherein the packet filtering circuit is a FPGA.

12. The method of claim 1 wherein the intelligent electronic device
further includes a processor electrically connected to the first internal
network port and the second internal network port, and wherein the
processor processes data received by the first internal network port
before processing data received by the second internal network port.

13. An intelligent electronic device comprising:i) an external network
interface adapted to receive network data;ii) a first internal network
port;iii) a second internal network port; andiv) a switching circuit in
electrical communication with the external network interface, the first
internal network port, and the second internal network port, wherein the
switching circuit examines the network data for a network data type
indicia and routes the network data to the first internal network port
when the network data type indicia is indicative of an urgent network
source.

14. The intelligent electronic device of claim 13 wherein the switching
circuit routes data to the second internal network port if the network
data type indicia is indicative of a non-real time network source.

22. The intelligent electronic device of claim 19 further comprising a
packet filtering circuit coupled to the external network interface, the
first internal network port and the first internal network port, wherein
the packet filtering circuit discards any data from a real time network
source not intended for the intelligent electronic device.

23. The intelligent electronic device of claim 22 wherein the packet
filtering circuit is a FPGA.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]None

FIELD OF THE INVENTION

[0002]The present invention relates generally to apparatus and methods for
communicating data to and from an intelligent electronic device and more
particularly to apparatus and methods of segregating urgent
communications from non-urgent communications within an intelligent
electronic device, so that the urgent communications can be dealt with
more promptly.

DESCRIPTION OF THE PRIOR ART

[0003]The modern power grid utilizes a sophisticated network of
Intelligent Electronic Devices ("IEDs") to ensure proper operation. For
example, IEDs commonly monitor various power line quantities, such as
voltage and current, to ensure that a given power line segment has not
become faulted. When a power line segment has been faulted, the IED
monitoring that segment will cause a circuit breaker or other form of
switchgear to operate to isolate the offending power line segment. When
an IED makes a determination to isolate a power line segment, in some
circumstances it may also send a communication to another IED to complete
the isolation of the power line segment from the power grid.

[0004]In addition to control data, such as that described above, IEDs
commonly communicate other data to one another and other devices involved
in power protection and control systems. IED communications have become
sophisticated enough that they use a wide variety of protocols.
Generally, however, IEDs utilize a single network connection, such as an
Ethernet connection. While the use of a single connection provides many
advantages, such as lower wiring, equipment, testing and labor costs, it
also presents certain challenges.

[0005]A network switch is a computer networking device that connects
network segments or endpoints. Network switches come in a variety of
types, such as Token Ring, Fibre Channel, and Ethernet, and can also be
used to connect varying types of network segments. An Ethernet switch is
a network switch that connects various Ethernet endpoints or network
segments together.

[0006]An Ethernet switch operates by saving the originating MAC addresses
of received frames, as well as the port on which a frame was received in
the switch's MAC address table. A switch will then selectively transmit
to an alternate port based on the frame's destination MAC address and
previous entries in the MAC address table. If a destination MAC address
is unknown, a broadcast address, or a multicast address, the switch will
transmit the frame out of all connected ports except for the one it was
received on. One last special case is where the destination MAC address
is the same as the originating MAC address, where the switch will simply
filter the frame out.

[0007]Most importantly, as described above, certain communications are
more urgent than other communications. For example, control data or real
time samples may only have value for a limited period of time, and,
accordingly, can be said to be more urgent than setup data from an
administrator, which may have value of a more permanent nature. For
example, an IED may receive urgent control data using IEC 61850 GOOSE
(Generic Object Oriented System Event), or preferably Mirrored Bits®.
The use of one physical connection makes it difficult for an IED to
discriminate between urgent data and non-urgent data. Generally, the
network stack looks at data in the order that it is received.

[0008]One prior art solution that IEDs have employed is for an IED to
incorporate a custom network stack that "snoops" received data frames for
urgent data, and processes those frames first. While this approach allows
more urgent data to be handled first it comes: i) at the cost of
significant processor time as it must search through received data, and,
ii) complexity in the form of a custom software stack.

OBJECTS OF THE INVENTION

[0009]Accordingly, it is an object of this invention to provide an
Intelligent Electronic Device and method for handling urgent received
data on a priority basis.

[0010]Another object of the invention is to provide an Intelligent
Electronic Device and method for handling urgent received data on a
priority basis without significantly increasing processor load.

[0011]Other advantages of the disclosed invention will be clear to a
person of ordinary skill in the art. It should be understood, however,
that a system, method, or apparatus could practice the disclosed
invention while not achieving all of the enumerated advantages, and that
the protected invention is defined by the claims.

SUMMARY OF THE INVENTION

[0012]The disclosed invention achieves its objectives by providing an
intelligent electronic device as well as a method operating within an
intelligent electronic device ("IED") to optimize the handling of network
data. Network data is received on an external network interface from, for
example, another IED. The network data is examined for a network data
type indicia and based on the network data type indicia, the data is
routed to a first internal network port or a second internal network
port, where urgent data is routed to the first internal network port and
non-urgent data is routed to the second internal network port.

[0013]In one embodiment, data may be routed to urgent and non-urgent ports
based on the network address that originated a particular frame of data.
For example, in an Ethernet system, the originating or destination MAC
address may serve as a network data type indicia to distinguish between
urgent and non-urgent Ethernet frames. Such an embodiment may utilize an
Ethernet switch internal to the IED to route data to Ethernet ports
within the IED.

[0014]In another embodiment, the underlying protocol that a frame adheres
to may be used as a network data type indicia, and cause data to be
routed to urgent and non-urgent ports. For example, IEC-61850 GOOSE data
or Mirrored Bits® data may be routed to the urgent port, while other
data may be routed to the non-urgent port.

[0015]In another embodiment that is particularly well-suited to be
employed within broadcast networks, such as Ethernet, a packet filtering
circuit may be employed. The packet filtering circuit may be
advantageously disposed between the external network connection and the
first internal network port, and will examine all received urgent frames
to filter out those frames that are directed to a different IED. This
will prevent a processing device from spending processing time servicing
urgent communications directed to a different IED.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]Although the characteristic features of this invention will be
particularly pointed out in the claims, the invention itself, and the
manner in which it may be made and used, may be better understood by
referring to the following description taken in connection with the
accompanying drawings forming a part hereof, wherein like reference
numerals refer to like parts throughout the several views and in which:

[0017]FIG. 1 is a simplified line schematic diagram of an electrical power
distribution system illustrating the use of intelligent electronic
devices supervising a power grid;

[0018]FIG. 2 is a block diagram of an intelligent electronic device that
segregates network data in accordance with this disclosure;

[0019]FIG. 3 is a simplified block diagram of a hardware solution to
segregate network data in accordance with this disclosure;

[0020]FIG. 4 is a simplified block diagram illustrating hardware and
software components within a microcontroller used to segregate network
data in accordance with this disclosure; and

[0021]FIG. 5 is a simplified block diagram of a hardware solution to
segregate network data in accordance with this disclosure and using
multiple external network ports.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

[0022]Turning to the Figures, and to FIG. 1 in particular, a power
distribution system 10 includes, among other components, a pair of
generators 12a and 12b configured to generate three-phase sinusoidal
power waveforms, such as, for example, 12 kV AC waveforms. Generally,
each generator will be protected by a circuit breaker; for example,
generator 12b is protected by circuit breaker 108, which is controlled by
IED 120. Also included are step up transformers 14a and 14b which are
configured to increase the generated waveforms to higher voltage
sinusoidal waveforms such as, for example, 138 kV AC waveforms.
Generally, each step up transformer will be protected by a pair of
circuit breakers; for example, step up transformer 14b is protected by
circuit breakers, which are controlled by IED 140. The step up
transformers operate to provide higher voltage waveforms to long distance
transmission lines 20a and 20b. As illustrated the generators and step up
transformers are part of a substation 16 and can be interconnected by a
bus 19 through the operation of a circuit breaker that is depicted but
not numbered.

[0023]A second substation 22 is depicted as including two step down
transformers 24a and 24b that are configured to transform the higher
voltage waveforms transported by the long distance transmission lines 20a
and 20b to a waveform that is more suitable for distribution to a load,
such as, for example, 15 kV AC. A bus 23 can interconnect different
distribution lines through the operation of a circuit breaker that is
depicted but not numbered.

[0024]A third substation 35 is depicted as including a third generator 12c
as well as an additional step up transformer 14c, and two step down
transformers 24c and 24d that connect to loads 30 and 34 respectively. A
bus 25 can interconnect the third substation 35 to the rest of the power
distribution system through transmission line 20c by operating a circuit
breaker that is depicted but not numbered.

[0025]FIG. 2 depicts an IED 200 integrating a network data segregating
scheme in accordance with this disclosure. A microcontroller 230
incorporates a CPU 232, program memory 234, which could be FLASH memory
or electrically-erasable ROM, and parameter memory 236, which could be
static RAM or dynamic RAM. As depicted the IED 200 examines one channel
of current, which is acquired by current transformer 204, low pass filter
214, and A/D converter 220. The IED also examines one channel of voltage
through potential transformer 206, low pass filter 216, and A/D converter
220. In addition, IED 200 accepts a number of binary inputs, and produces
a number of outputs, such as contact closures to control a circuit
breaker. Persons of skill in the art will understand that this is a
simplified view of an IED, which generally will examine numerous line
parameters including multiple current and voltage channels, as well as
incorporate many other functions.

[0026]An external Ethernet interface 250 is adapted to communicate with
other IEDs and other devices used within the power grid, such as
monitoring stations (not depicted). A switching device 252 examines
Ethernet frames that are received via Ethernet interface 250 and routes
the received frames down one of two paths based on a network data type
indicia contained within each frame. A first path handles urgent
communications, which are routed through filtering device 254 to a first
Ethernet port 238A. It should be noted that filtering device 254, which
is discussed in detail later in this disclosure, is a beneficial but
non-essential component of IED 200. A second path handles non-urgent
communications, which are routed to a second Ethernet port 238B. The
particular operation of switching device 252 is explained below.

[0027]Switching device 252 examines Ethernet frames received by Ethernet
port 250 to determine if a particular frame is of an urgent or non-urgent
nature. To accomplish this, the switching device 252 examines each
received frame for a network data type indicia. One possible indicia of
urgent network data is the source of the communications; within a
particular power grid, certain devices, such as other IEDs, are more
likely to source urgent communications than other devices, such as
monitoring computers. Another possible indicia of urgent network data is
the destination of the communications, as certain destination addresses,
such as multicast or broadcast addresses, can indicate that the data is
urgent network data. Accordingly, one way that switching device 252 can
make this determination is to use the MAC address from which each
Ethernet frame originated or to which the Ethernet frame is destined as a
network data type indicia, and then routing those frames received by
urgent communications sources, such as other IEDs, to the urgent
communications path, while routing non-urgent communications to the
communications path intended for non-urgent communications. In an
implementation adapted to take advantage of Ethernet MAC addresses,
switching device 252 could be an Ethernet switch integrated circuit.

[0028]Another way to determine if a communication is of an urgent nature
is to examine the contents of the data to determine what protocol the
data is communicating over, and use the underlying protocol as a network
data type indicia. For example, if a particular Ethernet frame contains
IEC-61850 GOOSE data, it is likely that the data is of an urgent nature.
In an implementation adapted to determine with which protocol a
particular frame was sent over, switching device 252 could be, among
other implementations, a custom field programmable gate array (FPGA) or
application-specific integrated circuit (ASIC).

[0029]It should be noted that combinations of the network data type
indicia recited above, as well as other network data type indicia that
have the property of indicating, in a broad sense, the type of data being
transmitted on the network, could be used in addition to or in place of
the network data type indicia described above.

[0030]Data may be sent from the microcontroller 230 by either or both
ports 238A and 238B. If all data is sent from one port, then the
switching device 252 and packet filtering device 254 essentially act as
pass through devices for data to the Ethernet interface 250. If data is
sent by both ports 238A and 238B, then the switching device may order
data sent from the urgent port 238A to be sent prior to data sent by the
non-urgent port 238B, with packet filtering device 254 still acting as a
pass through. This provides a minimal improvement in the delay of the
urgent data being received by other devices, without a corresponding
increase in the programming complexity of the microcontroller.

[0031]FIG. 3 illustrates one possible communications path 300 for use
within the IED 200. In particular, Ethernet interface 250 receives
network data from other devices associated with a power grid. Network
data is routed to an Ethernet switch IC 252. The Ethernet switch IC 252
operates to determine that network data originating from certain MAC
addresses or destined for certain MAC addresses will be routed as urgent
data to the first Ethernet port 238A and data that originates from other
MAC addresses or is destined for other MAC addresses will be routed as
non-urgent data to the second Ethernet port 238B.

[0032]As Ethernet is a broadcast network, messages received by IED 200 may
not be intended for that IED, but rather, for another device.
Accordingly, a packet filtering device 254 is used to discard any data
from the urgent route that is intended for a different IED prior to
delivering it to the microcontroller 230. In one embodiment of the
disclosed network data segregating system, the packet filtering device is
a FPGA 254 and is configured to discard any Ethernet frames that do not
contain expected destination MAC addresses. This will prevent the
microcontroller from examining, on an expedited basis, urgent
communications intended for another IED.

[0033]In certain systems, data may be urgent with regards to certain
devices, but not with regards to other devices. Accordingly, data
generated from a particular MAC address should be handled urgently by
some devices, but not by other devices. Accordingly, in another
embodiment the packet filtering device 254 can be adapted to
advantageously filter Ethernet frames on the source MAC address, to
determine if the frame originated from a set of urgent MAC addresses,
where the set can be configured on a device by device basis.

[0034]Certain embedded protocols may also include indications that data is
urgent. Accordingly, packet filtering device 254 can be adapted to
advantageously utilize embedded protocol information. One such example
would be the IED 61850 GOOSE APP ID field, and the packet filtering
device 254 can be adapted to only pass Ethernet frames where with a GOOSE
APP ID field that has certain characteristics.

[0035]It should also be noted that combinations of the above recited
filtering indicia could be utilized. For example, the packet filtering
device 254 could examine both the Ethernet frame destination MAC address
as described above, as well as the GOOSE APP ID field. Furthermore, more
complicated filtering schemes could be used as well. For example, the
packet filtering device 254 could initially filter on Ethernet frame
destination MAC address and GOOSE APP ID field, but, after receiving at
least one frame that met the required criterion, could then use the
source MAC address of the received Ethernet frame to treat all frames
generated by the corresponding device as urgent.

[0036]Data may be sourced from the microcontroller by either or both of
urgent port 238A and non-urgent port 238B. If data is sourced from only
one port, then FPGA 254 and Ethernet Switch IC 252 effectively act as
pass through devices for data sourced by microcontroller 230. However, if
data is sent from both ports 238A and 238B, the Ethernet switch IC 252
may be adapted to order data received from urgent port 238A so that it is
sent before data received from non-urgent port 238B, thereby providing a
slight improvement in the delay with which urgent data will be received
by other devices, without any additional complexity in programming of the
microcontroller.

[0037]FIG. 4 depicts a simplified block diagram of hardware and software
components within a microcontroller used to implement a network data
segregation system in accordance with an embodiment of this disclosure.
Ethernet frames are received on Ethernet ports 238A and 238B, which may
be integrated into microcontroller 230 as depicted. After being received,
frames are directed to the processing core 260, where urgent frames
received by port 238A are buffered in a first memory buffer 262, while
non-urgent frames received by port 238B are buffered in a second memory
buffer 264. Memory buffers 262 and 264 may be implemented as, for
example, a software FIFO, or some other data structure. The contents of
memory buffer 264 is then directed to non-urgent Ethernet stack 271. The
contents of memory buffer 262 is directed to urgent Ethernet stack 270,
which is optimized for processing urgent communications data. The
contents of either buffer may be directed frame by frame, or a block of
frames may be copied at once.

[0038]Contents of the urgent frame buffer 262 are handled on an expedited
basis. One way this may be accomplished would be to generate an interrupt
every time a frame is received by Ethernet port 252A, and to handle
processing of the frame within an interrupt handler. However, other
scheduling mechanisms could be used as well to ensure that urgent frames
are handled on an expedited basis.

[0039]Urgent Ethernet stack 270 and non-urgent Ethernet stack 271 may be
programmed to send data using either or both of ports 238A and 238B. If
programmed to send data using one port, then both urgent data and
non-urgent data is sent using the same port. Generally, if one port is
used, urgent data will be sent immediately, while non-urgent data will be
buffered until all urgent data has been sent. However, if both ports are
used, both urgent, and non-urgent data may be sent immediately, with the
ordering handled by the switching device (not depicted in FIG. 4).

[0040]FIG. 5 depicts an alternate embodiment of the disclosed network data
segregation system, including a pair of external Ethernet interfaces, as
opposed to the single network interface depicted in FIGS. 1-4. In
particular, Ethernet interfaces 250A and 250B receive network data from
other devices associated with a power grid. Network data is routed to an
Ethernet switch IC 252. The Ethernet switch IC 252 operates to determine
that network data originating from certain MAC addresses is routed as
urgent data to the first Ethernet port 238A and data that originates from
other MAC addresses is routed as non-urgent data to the second Ethernet
port 238B. The remainder of this figure operates similarly to the
embodiment described in the text corresponding to FIG. 3.

[0041]It should be noted that data can be received and transmitted by
either or both external Ethernet interfaces, with the Ethernet switch IC
252 operating as a general Ethernet switch or as a failover switch, using
one external Ethernet interface until a failure is detected, and then
switching to the other external Ethernet interface. It should also be
noted that while two external network ports are depicted in FIG. 5, a
person of skill in the art will realize that the disclosed network data
segregation system and method may be extended to an arbitrary number of
external network ports.

[0042]It should be noted that while Ethernet is depicted in the figures
and referred to throughout this specification, a person of skill in the
art will realize that other physical networking mediums could be used as
well. For example token ring networks, such as ARCNET and FDDI could be
used with the disclosed network data segregation apparatus, systems and
methods.

[0043]The foregoing description of the invention has been presented for
purposes of illustration and description, and is not intended to be
exhaustive or to limit the invention to the precise form disclosed. The
description was selected to best explain the principles of the invention
and practical application of these principles to enable others skilled in
the art to best utilize the invention in various embodiments and various
modifications as are suited to the particular use contemplated. It is
intended that the scope of the invention not be limited by the
specification, but be defined by the claims set forth below.

Patent applications by Robert E. Morris, Viola, ID US

Patent applications by Tony J. Lee, Pullman, WA US

Patent applications in class Input or output circuit, per se (i.e., line interface)

Patent applications in all subclasses Input or output circuit, per se (i.e., line interface)